Gels are finely dispersed systems of a liquid and a solid phase in which the solid phase forms a contiguous three-dimensional structure and the two phases are thoroughly intermingled. A distinction is made essentially between hydrophilic gels and hydrophobic gels. The latter are also known as oleogels. Oleogels are based on a nonpolar liquid, e.g., an oil, a wax or a paraffin, to which a gel-forming agent is added to achieve the desired physical properties.
Such oleogels may fulfill a variety of functions, depending on the composition.
Oleogels are used for topical application, in particular in the pharmaceutical field. In these pharmaceutical oleogels, a gel-forming agent is present in the gel in addition to the pharmaceutically active ingredients. Highly dispersed silicon dioxide, available under the brand name Aerosil®, is a widely used gel-forming agent for pharmaceutical oleogels. Oleogels are strongly thixotropic, i.e., they liquefy as a result of mechanical action and then solidify again. Other gels, e.g., gels containing pectin as the gel-forming agent, crosslink under the influence of an acid, while yet others undergo gelation as a function of temperature, e.g., gelatins.
Oleogels are also used industrially. An example is nonpolar coating agents (dripless paints). Highly dispersed silicon dioxide may also be used as the gel-forming agent for these applications. For industrial applications, this mineral gel-forming agent has the disadvantage that it does not burn without ash formation in thermal utilization of a product treated with such an oleogel.
Accordingly, it would be desirable to provide an oleogel-forming agent which is pharmaceutically active itself and burns without ash formation, an oleogel having such a gel-forming agent and a method for producing an oleogel having such a gel-forming agent.